Implement request id in PaymentDetailsInit

chrome/test/data/payments/payment_request_id.js

+/*
+ * Copyright 2017 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * Launches the PaymentRequest UI including a details.id and prints the
+ * resulting requestId.
+ */
+function buy() {  // eslint-disable-line no-unused-vars
+  try {
+    new PaymentRequest(
+        [{supportedMethods: ['visa']}],
+        {id: 'my_payment_id',
+         total: {label: 'Total', amount: {currency: 'USD', value: '5.00'}}})
+        .show()
+        .then(function(resp) {
+          resp.complete('success')
+              .then(function() {
+                print(resp.requestId);
+              })
+              .catch(function(error) {
+                print(error.message);
+              });
+        })
+        .catch(function(error) {
+          print(error.message);
+        });
+  } catch (error) {
+    print(error.message);
+  }
+}